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Casting Defects - Sand Mold, Metal Casting

Introducing various metal casting defects  with many pictures by Dandong Foundry in China. These are

the common sand casting defects  on the surface and inside of cast iron and cast steel parts.

1. Blowhole is a kind of cavities defect, which is also divide d into pinhole and subsurface blowhole.

Pinhole is very tiny hole. Subsurface blowhole only can be seen  after machining.

Blowhole Defect

2. Burning-on defect is also called as sand burning, which includes chemical burn-on, and metal

penetration.

Sand Burning Defect

3. Sand inclusion and slag inclusion are also called as scab or blacking scab. They are inclusion defects.

Looks like there are slag inside of metal castings.

Sand Inclusion Defect

4. Sand hole is a kind of shrinkage cavity defect. They are empty holes after sand blasting.

Main Casting Products

Stove Burner 

Cast Iron Plate

Manhole Cover Casting

Brake Drum

Warping Head Casting

Ductile Iron Belt Pulley

Cast Iron Flywheel

Boiler Ash Door 

Cast Iron Stove Grate

Tractor Gearbox

Pump BodyCast Iron Brackets

Cast Iron Weight

Gear Casting

Large Cast Steel Bracket

Cast Iron Drainage Pipe

Flange Castings

Cast Iron Pipe Fittings

Burner Grates for Gas Stove

Grey Iron Counter Weight

Cast Iron Axle Support

Cast Iron Blocks

Gas Burner 

Cast Iron Truck Castings

Cast Iron Tractor Parts

Cast Iron Stove Parts

Pump Shell and Valve Body

Cast Iron Umbrella Base

Cast Iron Pan, Cookware

Boiler Soot Collector 

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sand hole defect

5. Cold lap or also called as cold shut. It is a crack with round edges. Cold lap is because of low melting

temperature or poor gating system.

Cold Lap Defect

6. Joint flash is also called as casting fin, which is a thin projection out of surface of metal castings.

Joint flash should be removed during cleaning and grinding process.

Joint Flash Defect

7. Misrun defect is a kind of incomplete casting defect, which causes the casting uncompleted. The edge

of defect is round and smooth.

Misrun Defect

8. Shrinkage defects include dispersed shrinkage, micro-shrinkage and porosity.

Porosity Shrinkage Defect

9. Shrinkage cavities are also called as shrinkage holes, which is a type of serious shrinkage defect.

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Shrinkage Cavity Defect

10. Shrinkage depression is also a type of shrinkage defect, which looks like depressed region on the

surface of metal castings.

Shrinkage Depression Defect

11. Elephant skin is a type of surface defect, which cause irregular or wrinkle shapes surfaces.

Elephant Skin Defect

12. Veins defect is also called as rat tail, which looks like many small water flow traces on the surface

of metal castings.

Veins Defect

13. Rough surface, coarse surface is also a kind of surface defect. Normal rough surfaces can not be

 judged as defects, but too rough and uneven in surface will be a defect.

Rough Surface Defect

14. Mismatch in mold defect is because of the shifting molding flashes. It will cause the dislocation at

the parting line.

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Mismatch Mold Defect

15. Mechanical damage is because the damage during machining or delivery processes.

Mechanical Damage Defect

16. Slag inclusion is also called as exogenous inclusion, entrapped slag.

Slag Inclusion Defect

17. Raised mold defect. Because of the flotage of liquid metal, the mould flasks are raised, which

caused the top part of casting become higher or thicker than lower part.

Raised Mold Defect

18. Crack defects normally happen inside of metal castings. This defect will reduce the physical

properties of metal castings.

Crack Defect

19. Abnormal nodulizing or under-nodulizing defects. Because of many reasons, the spheroidization of 

graphite for ductile iron will be affected, therefore, caused the bad spheroidization rate.

 

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Abnormal Nodulizing Defect

20. Uneven hardness defect means the uneven hardness on the same surfaces. When machining to

harder positions, the machining will become more difficult.

Uneven Hardness Defect

21. Sand drop is also called as sand crush. The sand mold drops part of sand blocks, so they will cause

the similar shaped sand holes or incomplete.

Sand Drop Defect

22. Deformation will cause the oversized tolerance for flatness and straightness. This is very common

defect for long castings, and flat castings with thin wall thickness. The reasons are the natural

deformation during cooling process in sand molds, or in air, sometimes, the overly sand blasting also

could cause this problem.

Deformation Problem

23. After welding repair, even after machining or grinding, the welding marks will still be visual. As for

unimportant casting surfaces, if the client allow welding repair, then these marks should be acceptable.

But for high pressure-bearing positions, or the client has clearly forbidden any welding repair, then

these marks will be taken as defects.

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Welding Repair Marks

24. Chill iron could effectively reduce the shrinkage for the key positions, so using chill iron is very

common in iron foundries. However, the edges of chill irons could be clearly found by visual inspection.

Some clients will not require to grind them if these marks do not affect the appearance. However, the

clients could require the casting manufacturer to grind them just for better surface looking. Please

clearly notice that these marks should not be judged as the casting defects. Refer to iron-foundry.com.

Chill Iron Marks

25. Chill defects are also called as "casting chilling defects". The surface of the castings with this defect

will be extremely white, shiny and smooth. The left one of the parts on the following photo is showing

this defect. The defective castings will be fragile and crispy, so during machining, some edges and tips

will be broken. This defect was caused by the low temperature of sand molds, and prematurely out of 

sand molds, so the hot iron become chilled quickly. The proper annealing heat treatment to them could

solve this defect.

Casting Chilling Defects

26. Massive free carbide. This is a defect of material, normally happen on ductile iron. Because of 

inverse chilling defects and poor inoculation, there will be mass free carbide, which will cause fragile,

poor welding property to ductile iron castings. High temperature annealing heat treatment could

improve it.

Massive free carbide

27. Internal sweating, or called as cold short, short iron. There are iron beans in the castings. This is

because of unreasonable gating design, which caused some liquid iron became beans suddenly, then

these beans were wrapped by other liquid irons. This is a surface defect, but will cause serous problem

if they located in key positions.

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Internal sweating, cold short, short iron

28. Stripping defect. There is very thin iron skin on the surface of castings. Two layers. This is because

of unreasonable gating system, which caused very thin air layers existed. This defect is a surface

defect, so normally it can be grinded off. However, it should be discarded if it is not just on the surface.

Stripping defect

 

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